Primary Confinement System

DOE-HDBK-1132-99

their ventilation systems. Tertiary or final confinement should be the building

structure and its ventilation system.

Primary Confinement System. UEU cladding or storage containers typically

provide primary confinement during normal operation, anticipated operational

occurrences, and accidents. Cladding or storage containers are used to provide

a corrosion-resistant confinement for the fuel assemblies and other UEU to

prevent an uncontrolled release of radioactive material. Special design features

should be considered to introduce, remove, and handle UEU safely. These

handling systems and equipment should protect against the dropping of storage

containers, UEU assemblies, and other items onto the stored UEU.

Secondary Confinement System. The compartments and their ventilation

systems comprise the secondary confinement system. Penetrations of the

secondary confinement barrier should have positive seals to prevent the

migration of contamination. The use of positive seals should be considered for

penetration of enclosures within the facility building to provide proper ventilation

flow paths and to prevent the migration of contamination within the facility.

The need for special ventilation systems for confinement purposes should be

determined based on the safety analysis. In general, each compartment should

be supplied with ventilation air from the building ventilation system. Separate

exhaust ventilation should be handled by a system with sufficient capacity to

provide adequate ventilation flow in the event of a credible breach in the

compartment confinement barrier. Pressure in the compartments should be

negative with respect to the building ventilation system.

Tertiary Confinement System. The facility' building and ventilation system

comprise the tertiary confinement system. Penetrations of the building

confinement barriers should have positive seals to prevent the migration of

contamination.

1.2.3

Uranium Processing and Handling Facilities. The following provisions are

typical for a uranium processing and handling facility (UPHF) confinement

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